Silicone-urethane polymers (i.e., silicone-polyurethanes or polydimethylsiloxane-polyurethanes) are a class of materials that was developed to fill the need for soft biostable materials needed in implantable medical devices. Such materials are commercially available from sources such as Aortech (e.g., under the tradename Elast-Eon E2A) and DSM (e.g., under the tradename PurSil 35). The entire industry believed that this was the answer to the need for oxidatively stable materials. It was generally believed that because silicone-polyurethanes as a class of materials were considered primarily polyurethane, this improved oxidative stability was sufficient for many uses.